U.S. patent number 6,074,559 [Application Number 08/976,156] was granted by the patent office on 2000-06-13 for filter device having a hollow fiber bundle and associated sealing devices.
This patent grant is currently assigned to Fresenius Medical Care Deutschland GmbH. Invention is credited to Uwe Hahmann, Klaus Heilmann, Michael Schonhofen, Gerhard Wiesen.
United States Patent |
6,074,559 |
Hahmann , et al. |
June 13, 2000 |
Filter device having a hollow fiber bundle and associated sealing
devices
Abstract
A filter device has two flow paths. The first flow path has at
least one cap and fluid port. The second flow path surrounds the
first fluid flow path and has at least one cap that overlaps the
cap of the first fluid flow path. The second flow path also has at
least one fluid port. The filter device provides a simple
arrangement that is easily disinfected or sterilized.
Inventors: |
Hahmann; Uwe (St. Wendel,
DE), Heilmann; Klaus (St. Wendel, DE),
Schonhofen; Michael (St. Wendel, DE), Wiesen;
Gerhard (St. Wendel, DE) |
Assignee: |
Fresenius Medical Care Deutschland
GmbH (Bad Homburg, DE)
|
Family
ID: |
27438491 |
Appl.
No.: |
08/976,156 |
Filed: |
November 12, 1997 |
Foreign Application Priority Data
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Nov 21, 1996 [DE] |
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196 48 275 |
Nov 21, 1996 [DE] |
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196 48 276 |
Jun 26, 1997 [DE] |
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197 27 250 |
Oct 7, 1997 [DE] |
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197 44 336 |
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Current U.S.
Class: |
210/645;
210/321.79; 210/321.8; 210/321.88; 210/321.89; 210/450; 210/455;
210/500.23; 210/646 |
Current CPC
Class: |
B01D
63/02 (20130101); B01D 63/022 (20130101); B01D
63/023 (20130101); B01D 65/00 (20130101); B01D
2313/20 (20130101) |
Current International
Class: |
B01D
63/02 (20060101); B01D 65/00 (20060101); B01D
061/24 (); B01D 061/28 (); B01D 063/02 () |
Field of
Search: |
;210/645,646,321.79,321.8,321.88,321.89,450,455,500.23 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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305 672 |
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Mar 1989 |
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EP |
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0 305 687 |
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Mar 1989 |
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EP |
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30 39 307 |
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Apr 1981 |
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DE |
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2646358 |
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May 1982 |
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DE |
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40 36 978 |
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May 1992 |
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DE |
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2 135 902 |
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Sep 1984 |
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GB |
|
Primary Examiner: Kim; John
Attorney, Agent or Firm: Kenyon & Kenyon
Claims
What is claimed is:
1. A filter device comprising a housing, a first fluid flow path
contained in said housing, a molding compound adjacent the ends of
the first fluid flow path, a first fluid port for fluid inflow and
outflow from said first fluid flow path, a first cap joined to said
molding compound and the first fluid port, a second cap connected
to said housing and overlapping said first cap, a second fluid flow
path between said first and second caps and in a space between the
housing and the first fluid flow path, a second fluid port
providing fluid inflow and outflow from the second fluid flow path,
a ring having projections and having axial notches in fluid
communication with said second fluid flow path.
2. The device of claim 1 wherein said housing is generally
cylindrical in shape.
3. The device of claim 2 wherein said housing is widened at at
least one end such that the portion of the housing joining said
second cap has a diameter greater than the remainder of said
housing.
4. The device of claim 2 wherein the housing has, near at least one
end, a flange extending radially outwardly and connected to said
second cap.
5. The device of claim 2 wherein said molding compound is a
hardened disk.
6. The device of claim 2 wherein the outer margins of said
projections are bound in the molding compound such that portions of
said notches free of molding compound are in fluid communication
with said second fluid flow path.
7. The device of claim 2 wherein said projections are scalloped or
tooth-like.
8. The device of claim 2 wherein said projections have secondary
projections extending radially outwardly from said projections.
9. The device of claim 2 wherein the circumferential distance
between said projections is greater than the circumferential width
of said projections.
10. The device of claim 6 wherein the cross-sectional area of said
notches increases with the increasing circumferential distance of
each notch from a fluid port positioned at a predetermined radial
location.
11. The device of claim 10 wherein fluid flow through each of said
notches is substantially equal when fluid is introduced from said
fluid port.
12. The device of claim 1 wherein said first fluid flow path
consists of a hollow-fiber bundle.
13. The device of claim 6 further comprising a saucer-shaped ring
having radial legs with bore holes therein, said legs being
connected to the inside wall of said housing, such that said
notches open into an annular space defined by said saucer-shaped
rings.
14. The device of claim 13 wherein the saucer-shaped rings are
u-shaped.
15. The device of claim 2 wherein at least one of said first and
said second fluid ports extends in an axial direction.
16. The device of claim 2 wherein at least one of said first and
said second fluid ports extends in a radial direction.
17. The device of claim 6 wherein the ring is made of a material
which does not form a tight adhesive bond with the molding
compound.
18. The device of claim 17 wherein the ring is made of
polypropylene.
19. The device of claim 2 wherein the molding compound is made of a
polyurethane.
20. The device of claim 2 wherein the first cap is connected to the
molding compound in a fluid-tight manner.
21. The device of claim 20 further comprising an o-ring between
said first cap and said molding compound.
22. The device of claim 2 wherein said second cap is connected to
said housing in a fluid-tight manner.
23. The device of claim 2 wherein the projections in said ring are
bound in said molding compound and radial bore holes are provided
in said housing, said bore holes in fluid communication with said
second fluid flow path.
24. The device of claim 23 further comprising a saucer-shaped ring
having radial legs with bore holes therein, said legs being joined
to the inside wall of said housing, such that said bore holes open
into an annular space defined by said saucer-shaped rings.
25. A dialysis filter comprising a housing, a first fluid flow path
contained in said housing, a molding compound adjacent the ends of
the first fluid flow path, a first fluid port for fluid inflow and
outflow from said first fluid flow path, a first cap joined in a
fluid-tight manner to said molding compound and the first fluid
port, a second cap connected to said housing in a fluid tight
manner and overlapping said first cap, a second fluid flow path
located between said first and second caps and further located in a
space between the housing and the first fluid flow path, said
housing widened at one or both ends such that the portion of the
housing connected to said second cap has a diameter greater than
the remainder of said housing, a second fluid port providing fluid
inflow and outflow from the second fluid flow path, a ring having
projections and having axial notches, the margins of said
projections being bound in said molding compound such that a
portion of said notches is free of molding compound, the portion of
said notches free of molding compound being in fluid communication
with said second fluid flow path.
26. The device of claim 25 wherein said housing has, adjacent the
widened portion of said housing, an annular flange extending
radially outwardly, said second caps being connected to said flange
in a fluid-tight manner.
27. The device of claim 25 wherein said projections are bound in
molding compound and bore holes are provided in said housing, said
bore holes in fluid communication with said second fluid flow
path.
28. The device of claim 25 further comprising a saucer-shaped ring
having radial legs with bore holes therein, said legs being joined
to the inside wall of said housing, such that the annular space
formed by said saucer-shaped ring is in fluid communication with
said second fluid flow path.
29. The device of claim 25 wherein said fluid ports are axially
oriented.
30. The device of claim 25 wherein said fluid ports are radially
oriented.
31. The device of claim 25 wherein the cross-sectional area of the
free portions said notches increases with the increasing
circumferential distance of each notch from a fluid port positioned
at a predetermined radial location, such that fluid flow through
each of said notches is substantially equal when fluid is
introduced from said radially located fluid port.
32. The device of claim 27 wherein the cross-sectional area of the
bore holes increases with the increasing circumferential distance
of each bore hole from a fluid port positioned at a predetermined
radial location, such that fluid flow through each of the bore
holes is substantially equal when fluid is introduced from said
radially located fluid port.
33. The device of claim 25 wherein said first flow path consists of
a hollow-fiber bundle.
34. A method of filtering a fluid comprising the step of providing
a filter device comprising a housing, a first fluid flow path
contained in said housing, a molding compound adjacent the ends of
the first fluid flow path, a first fluid port for fluid inflow and
outflow from said first fluid flow path, a first cap joined to said
molding compound and the first fluid port, a second cap connected
to said housing and overlapping said first cap, a second fluid flow
path between said first and second caps and in a space between the
housing and the first fluid flow path, a second fluid port
providing fluid inflow and outflow from the second fluid flow path,
a ring having projections and having axial notches in fluid
communication with said second fluid flow path, and further
comprising the steps of flowing a first fluid through the first
fluid flow path and flowing a second fluid through the second fluid
flow path, impurities from said first fluid diffusing into and said
second fluid, said second fluid with said impurities flowing out of
said second fluid flow path through said second fluid port.
35. The method of claim 34 wherein the first and second fluids flow
in counter-current.
36. The method of claim 34 further comprising the step of
positioning the filter device, for at least a portion of the period
of operation, such that gas bubbles cannot collect in said flow
paths.
37. The method of claim 36 wherein said filter device is positioned
vertically and said first and second fluid ports attach to fluid
supply and discharge lines such that gas bubbles cannot collect in
said flow paths.
38. The method of claim 34 further comprising the steps of flowing
said first fluid through said molding compounds and through said
first fluid flow path and exiting said device through said first
fluid port, and flowing said second fluid into the second fluid
flow path, said second fluid spreading out in the space between
said first and second caps and flowing through said axial notches
into the space between said housing and said first fluid flow path,
said second fluid flowing over said first fluid flow path, said
second fluid flowing through said notches into said space between
said first and second caps and exiting said device.
39. The method of claim 34 wherein the projections in said ring are
bound in said molding compound and radial bore holes are provided
in said housing, said bore holes in fluid communication with said
second fluid flow path, the device further comprising a
saucer-shaped ring having radial legs with bore holes therein, said
legs being joined to the inside wall of said housing, such that
said bore holes open into an annular space
defined by said saucer-shaped rings, said second fluid flowing from
the space between said first and second caps through said bore
holes in said housing into said annular space and through said bore
holes in said radial legs into the space between said housing and
said first fluid flow path.
40. A filter device comprising a housing, a first fluid flow path
comprising a hollow fiber bundle contained in the housing, a
molding compound adjacent the ends of the first fluid flow path, a
second fluid flow path located between the housing and the first
fluid flow path, a first fluid port in fluid communication with the
first fluid flow path, a second fluid port in fluid communication
with the second fluid flow path, the second fluid port oriented
such that, during use, no air bubbles may collect in the second
fluid flow path, a cap provided at each end of the housing and
joined to the housing in a fluid-tight manner, and an annular space
in fluid communication with said second fluid flow path and said
second fluid port wherein the device further comprises a ring
having projections and axial notches in fluid communication with
said annular space.
41. The device of claim 40 wherein during normal use the second
fluid port is in fluid communication with the top of the annular
space.
42. The device of claim 40 wherein the second fluid port is
oriented substantially parallel to the direction of fluid flow in
the second fluid flow path.
43. The device of claim 40 wherein the second fluid port projects
radially.
44. The device of claim 40 wherein the housing is widened each end
such that the portion of the housing joining the caps has a
diameter greater than the remainder of said housing.
45. The device of claim 40 wherein the first and second fluid flow
paths are sealed off from one another by O-rings between the
molding compounds and the caps.
46. The device of claim 45 wherein the molding compound has a
circumferential groove into which the O-ring can be seated.
47. The device of claim 40 wherein the caps are produced by
injection molding.
48. The device of claim 40 wherein the first and second fluid ports
further comprise connection pieces constructed to sealingly press
the ports into connection with a dialysis machine.
49. The device of claim 40 wherein the caps are butt-joined to the
housing.
Description
FIELD OF THE INVENTION
The invention relates to a filter device having two flow spaces, of
which a first space, preferably a permeate space, is formed by the
tubular or capillary tube passages of a hollow-fiber bundle poured
at its ends into a molding compound, and a second space, preferably
a filtrate space, is formed by a housing enclosing the fiber
bundle, the first space being sealed off by caps, placed on the
molding compounds, with sealing devices running over the peripheral
areas of said molding compounds, and the molding compounds being
braced against the housing.
BACKGROUND OF THE INVENTION
The German laid open print 26 46 358 discloses a filter device in
which the hollow-fiber bundle encloses a central conduit in a
ring-like manner, and the ends of the ring-shaped hollow-fiber
bundle are sealed off by a molding compound both with respect to
the central conduit and with respect to the housing casing
concentrically enclosing it.
Another known filter device likewise comprises a tubular housing
which encloses the hollow-fiber bundle, the ends of the
hollow-fiber bundle being joined to the ends of the tubular housing
by a molding compound. In this filter device, the housing is
provided in each case with radial connection pieces, adjacent to
the molding compounds, which form the inlets and outlets to the
second flow space. The capillary tubes of the hollow-fiber bundle
enclosed by the molding compounds are cut at their end faces to
open them. Caps provided with connection pieces which form the
inlets and outlets of the first flow space are then placed
sealingly on the ends of the tubular casing.
These known filter devices are used, for example, as capillary
dialyzers, the flow spaces formed by the capillary-tube passages
forming the blood chamber, and the housing enclosing the
hollow-fiber bundle forming the dialysate chamber in which the
dialysate flows around the hollow fibers.
The problem existing in the known filter devices is that the
molding compound, usually made of PU [polyurethane fiber], which
hardens in a disk shape and forms a sealing between the two flow
spaces, shrinks when hardening, so that stresses develop in the
disk-shaped sealings formed by the molding compounds which can lead
to cracks and even detachments of the molding compounds from the
housing casing enclosing them. As a result, the two flow spaces are
no longer completely sealed off from one another, and the adhesion
of the sealing compounds to the housing enclosing the fiber bundle,
said adhesion producing the seal, is no longer reliably
assured.
In a filter device of the type indicated at the outset disclosed by
EP 0 305 687 B1, the disk-shaped molding compounds are enclosed by
interposed rings to which the molding compounds do not adhere, so
that they can shrink free of stress. This stress-free shrinking
prevents cracks in the
disk-shaped molding compounds, and makes it possible to dispense
with a direct sealing between the peripheral edge of the sealing
compounds and the housing enclosing them. To nevertheless maintain
a sealing between the two flow spaces, the first space is sealed
off by caps placed on the molding compound, and specifically by
sealing devices which run over the edge area of the molding
compound and against which the caps are pressed.
In this known filter device, the problem now exists of producing a
connection to the second space formed by the housing enclosing the
fiber bundle. This connection is produced in the known filter
device, in that the diameter of the tubular housing is widened at
its end areas more or less in the manner of a sleeve, these widened
areas being provided with radial connection pieces. These
connection pieces open through into the second space formed by the
housing, the widened sections of the housing being sealed off from
the first space because the caps are sealingly joined to the
widened sections, so that a sealing is produced to the outside by
the cap edge, and a sealing is produced with respect to the first
space by the circumferential sealing ring. This type of arrangement
of the connection pieces at the second space formed by the housing
is relatively costly. Furthermore, dead spaces which are poorly
rinsed develop above or below the connection pieces, at which gas
bubbles can collect. This can have a disadvantageous effect during
disinfecting or sterilization, as well as generally when
handling.
OBJECTS AND SUMMARY OF THE INVENTION
Therefore, the object of the invention is to produce a filter
device of the type specified at the outset in which, on one hand,
it is reliably assured that the two flow spaces are sealed off from
one another by the hardened molding compounds, and on the other
hand, a simple arrangement of the connection pieces for the second
flow space is produced and poorly rinsed dead spaces are moreover
avoided.
This objective is achieved according to the invention, given a
filter device having two flow spaces, the first space formed by
tubular or capillary tube passages of a hollow-fiber bundle, said
fiber bundle being poured at its ends into a molding compound, and
a second space formed by the housing surrounding the fiber bundle.
The invention further entails the first space being sealed off by
caps, placed on the molding compounds, with sealing devices being
placed over the peripheral areas of the molding compounds, and the
molding compounds being braced against the housing. The molding
compounds are hardened in molds enclosing them at their end faces
and peripheral sides to form disks. Caps are provided for the ends
of the first space that seal to the molding compound and have a
connection piece providing inflow/outflow access to the first
space. A second set of caps, overlapping the first caps, is
provided, said caps having a connection piece providing
inflow/outflow access to the second space. The edges of the second
caps being joined to the housing in a fluid tight manner, so that
between the first and second set of caps, interspaces are formed,
said interspaces being connected to the second space.
In the filter device according to the invention, the molding
compounds are hardened in molds enclosing them on the face and at
their sides, so that the molding compounds are able to shrink free
of stress. As in the known filter device, the sealing between the
disk-shaped molding compounds thus formed and the first caps is
effected by inserted sealing means. However, to produce a simple
access to the second flow space, the corresponding connection
pieces are no longer arranged on the housing itself, but on the
second cap overlapping the first cap. This simplifies the filter
device.
The inner edges of the second caps overlapping the molding
compounds advantageously extend beyond the molding compounds to the
inside, so that a flow space is produced between the
circumferential wall of the second caps and the molding compounds
or the fiber bundles enclosed by them.
According to a preferred specific embodiment, the
pipe-section-shaped housing, into which the hollow-fiber bundle is
drawn, is provided at the ends of its casing with tooth-like or
scalloped projections formed by axial notches or indentations
running out freely, the outer areas of the projections being
integrated into the molding compounds, so that the free inner areas
of the notches or indentations form flow passages for the fluid.
Since the housing, which is pipe-section-shaped or preferably
provided with a circular cross-section, is made of a material
having elastic properties such as PC (polycarbonate), wreath-shaped
edges made of flexible tongues are formed by the notches or
indentations, said edges being at least partially enclosed by the
molding compound. When the molding compound then hardens to form
the disks, they can shrink essentially free of stress, because the
flexible tongues offer no significant resistance to this shrinking.
According to this refinement of the present invention, the disks
formed by the molding compounds are firmly joined to the ends of
the tubular housing, so that the two flow chambers can then be
reliably separated from one another by the two caps overlapping one
another, with the appropriate sealing means.
It may be that the filter device known from EP 0 305 387 B1 has a
tubular housing, in which wreath-shaped edges formed by notches or
indentations are produced in the widened end sections and are
partially enclosed by the molding compounds hardened to form disks.
However, these wreath-shaped edges made of rectangular projections
demand a complicated design of the housing, because in addition,
they are still enclosed by the widened end sections of the housing
which are provided with the connection pieces.
The housing is expediently provided in the area of the inner ends
of the projections with radial flanges, on which the edges of the
second caps are sealingly supported, or to which they are
secured.
Advantageously, the distance of the projections from one another in
the circumferential direction is greater than their width.
According to one inventive embodiment, for which independent
protection is claimed, the cross-sectional area of the regions of
the notches or indentations free of the molding compounds is so
dimensioned that, starting from a radial connection piece, they
increase in their cross-section, so that essentially equal partial
quantities of the fluid can enter and exit through the
cross-sections. This embodiment takes into account the circumstance
that, in the annular space surrounding the fiber bundle and into
which the liquid is fed through a radial connection piece, a
pressure drop occurs in the circumferential direction starting from
the mouth of the connection piece. Adjusting the cross-sections of
the intake ports to this pressure drop assures that essentially
equal quantities of fluid enter the openings distributed over the
circumference.
A special problem in filter devices of the type indicated at the
outset is assuring that in the second space, the surfaces of the
fibers in the hollow-fiber bundle are circumflowed as completely
and uniformly as possible by the introduced fluid, in order to
increase the effectiveness of the filter device. Therefore,
according to one particularly preferred specific embodiment of the
invention, inserted into the housing are saucer-shaped rings whose
legs are joined to the inside wall of the housing and which are
provided with bore holes, and that the inside wall is provided with
bore holes opening through into the annular spaces formed by the
rings. An annular space is formed by the saucer-shaped ring, in
which the introduced fluid can spread out well. The bore holes can
be distributed uniformly over the periphery, in doing which the
cross-sections of the bore holes can be adapted to the pressure
drop occurring in the introduced fluid if it is fed into the
annular space only through one bore hole or one radial connection
piece.
To maintain an essentially uniform fluid pressure given a one-sided
introduction of the fluid into the annular space, the bore holes
and openings respectively having identical flow-through
cross-sections can be distributed with appropriately variable
clearances over the periphery of the inside wall of the annular
space.
Advantageously, the rings have a U-shaped cross-section, the bore
holes being arranged in the radial legs of the rings.
In the known filter device, the annular spaces formed by the
annular grooves have an axial clearance with respect to the end
disks formed by the molding compounds. Because of this, in the case
of a vertically standing filter device, for example, air bubbles
can collect at the upper disk formed by the molding compound.
Furthermore, air bubbles can also collect in the lower annular
groove between the mouth of the radial connection piece and the
groove bottom. A result of this undesired collecting of air or air
bubbles is that, for example, during sterilization or disinfection
of the filter, the air-filled areas do not come in contact, or come
only insufficiently in contact with the sterilizing or disinfecting
means.
To achieve a complete deaeration of the hollow-fiber space, a
further inventive development provides that the annular spaces or
the passages connecting the annular spaces to the second space are
joined directly to the molding compounds, or extend in the axial
direction to their area.
This refinement of the present invention prevents dead spaces
between the connection pieces and the annular spaces respectively
into which they discharge, so that no air can accumulate in
unwanted manner in dead spaces, and a complete circumcirculation of
the hollow-fiber bundle by the fluid between the molding compounds
is assured.
Expediently, both sides of the filter are identically shaped, so
that the effects provided according to the invention are attainable
in any position of the filter.
The embodiment of the filter according to the invention also has a
favorable effect on the discharge side of the second space, since
the fluid is withdrawn from the second space essentially uniformly
distributed over the annular space.
A further advantage of the present device is that its housing can
be made of a material such as propylene which does not form a tight
adhesive bond with the molding compound. Therefore, it is possible
to produce the filter device according to the invention from less
costly plastic materials, which increases its economic
efficiency.
A further inventive refinement relates to a filter device having
two flow spaces, of which a first space, preferably a permeate
space, is formed by the tubular or capillary tube passages of a
hollow-fiber bundle poured at its ends into a molding compound, and
a second space, preferably a filtrate space, is formed by a housing
enclosing the hollow-fiber bundle. The filtrate space is sealed off
from the inlets and outlets of the tubes of the hollow-fiber bundle
by the molding compound. Furthermore, at least two connection
pieces are provided for the feeding and removal of fluids into or
out of each of the two spaces, of which at least one connection
piece of the second space opens through into an annular space
formed between the housing and the area of one end of the
hollow-fiber bundle. To assure that there is no dead space in the
annular space in which air bubbles can collect, the present
invention provides that in the position of normal use, at least one
annular space is located at the top, and that the annular space
extends to the supply line and discharge line respectively.
Preferably dialysate can be fed or removed through the upper
annular space.
In the following, an exemplary embodiment of the invention is
explained in more detail with the aid of the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a longitudinal cross-section through one side of a
filter device according to the invention,
FIGS. 2 to 4 show top views onto one end face of a disk formed by
the molding compound,
FIG. 5 shows a longitudinal cross-section through the housing of a
known filter device,
FIG. 6 shows a section through the upper area of the housing of a
filter device according to the invention with closed annular
space
FIG. 7 shows a side view of a filter device according to the
invention and
FIG. 8 shows a section through the filter device according to FIG.
7.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Filter device 1 is made of a pipe-section-shaped housing 2 of
plastic such as PC, whose edges merge into a radial, annular flange
3. Joined to the housing, to the inner edge area of this flange 3
or to the transition region between the cylindrical pipe section
and the flange, is a cylindrical ring which is provided with
indentations 5 that form rectangular notches which run out freely.
Formed between these notches 5 are scallop-like or tongue-like
projections 4 which are likewise essentially rectangular and extend
in the axial direction. At their upper, outer, end areas, these
projections 4 have projections 6 pointing radially outwardly.
A hollow-fiber bundle 55 is introduced into pipe-shaped housing 2.
The ends of this hollow-fiber bundle are embedded in a molding
compound 7 made, for example, of PU, which is disk-shaped after
hardening. Since during its hardening, the molding compound is
centrifuged about an axis of rotation at right angles to housing
axis 8, disk 7 in the top view evident from FIG. 1 has a
cylindrical saucer-shaped inner side 9. The hardening is carried
out in a cap which rotates along and which delimits the end face
and the peripheral side. The tolerance range within which
cylindrical, saucer-shaped, inner side 9 can move is indicated by
broken lines 9' and 9".
After hardening the molding compound, disk 7 is cut at its end face
10, thus opening the small capillary tubes of the hollow-fiber
bundle embedded in the molding compound.
A first cap 11 having a central connection piece 12 is then placed
on end face 10 of disk 7, said cap being sealed off at its edge
area, by means of an O-ring 13, from the edge area of disk 7 free
of hollow fibers.
First cap 11 is enclosed by a second cap 14 having a cylindrical
wall 15 whose edge area is joined in a fluid-tight manner to the
outer edge of annular flange 3. Second cap 14 possesses a central,
cylindrical extension prolongation 16 which forms a connection
piece and concentrically encloses the double-walled connection
piece 12 of first cap 11. Second cap 14 is provided on its inner
side with ray-shaped webs 17 which assure the necessary clearance
to first cap 11, and thus define flow channels. Cylindrical
extension prolongation 16 is also provided on its inner side with
radial webs 19 which are supported on the outer casing of
connection piece 12 and define flow channels.
Radial webs 20, arranged in a star shape and used as stiffening,
are provided on the lower side of first cap 11.
With its cylindrical edge 15, second cap 14 encloses, with radial
clearance, disk 7 and scalloped or tooth-shaped extension
prolongations 4, thus forming an annular space 21 through which the
fluid, introduced through connection piece 16, can enter through
the inner areas of ports 5 into the flow space enclosing the
hollow-fiber bundle.
As FIGS. 2 to 4 show, the tooth-like or scallop-like projections 4
and gaps 5 formed between them can have different lengths and form
different angles at circumference. The nose-shaped, radial
projections 6 can also vary in length and width.
FIG. 5 shows a longitudinal cross-section through the housing of a
known dialyzer. In this known dialyzer, the ends of hollow-fiber
bundle 25 are enclosed by the molding compounds which have hardened
to form disks 26 and which form secure bonds to outer edges 27, 28
of housing 29. At a distance from disks 26, the housing is provided
with radial connections 30, 31 that open into channel-shaped
annular spaces 32, 33 which, in the manner shown, are formed by
inner, ring-shaped wall sections 34, 35 which run out freely and
whose edges terminate with axial clearance before the disks. If,
for example, given a vertically standing housing, a fluid such as
dialysate is introduced through lower radial connection piece 31
into the space accommodating hollow-fiber bundle 25, the fluid
tends to overflow the edge of wall 35 bordering annular groove 33,
mainly in the areas near connection piece 31, so that an
unsymmetrical fluid flow, that is to say dialysate flow, develops
in housing 29.
The filter device according to the invention, explained with the
aid of FIGS. 1 to 4, prevents this unsymmetrical flow, because the
fluid or dialysate spreads out in annular space 21 and then,
essentially with
uniform circumferential distribution, enters through the inner,
free areas of inlet ports 5 into the space enclosing the
hollow-fiber bundle. In the exemplary embodiment shown, annular
space 21 is bounded outwardly by the cylindrical wall of cap 15,
the cap being provided with an axial, concentrically arranged
intake nipple, so that the fluid spreads out with equal pressure in
annular space 21. Since an essentially equal fluid pressure occurs
over the periphery of annular space 21, the intake ports formed by
the free areas of inlet notches 5 can also have equal
cross-sections.
In the exemplary embodiment according to FIG. 6, the fluid or the
dialysate enters through radial bore holes 41 of
pipe-section-shaped housing 36 into an annular space 37 which is
formed by a U-shaped ring 38 whose outwardly-pointing legs are
joined in a fluid-tight manner to the housing casing. Provided in
the legs of U-shaped ring 38 are bore holes 39, uniformly
distributed over the circumference, through which the fluid
introduced into annular space 37 can enter into the chamber
containing the hollow-fiber bundle.
The pipe-section-shaped housing is provided, in the area of the
lower side of the annular space, with an outer, radially
circumferential flange 40 upon which the edge of a cap can be
placed, in a corresponding manner as in the case of the device
described with the aid of FIGS. 1 to 4, so that between the
cylindrical circumferential wall of the cap and the upper part of
housing 6, an annular space is formed through which fluid can be
conducted, with equal pressure distribution, to radial bore holes
35 distributed over the periphery of the housing.
FIG. 7 shows a side view of a filter device, in the case shown, a
dialyzer. In this dialyzer, the connections or connection pieces
used for connecting to the nozzles of a dialysis machine are
located on one side and have center lines parallel to one another,
so that they can be sealingly pressed, directly or through a
suitable device, onto the nozzles of the dialysis machine.
In the filter device evident from FIGS. 7 and 8, the upper and
lower caps provided with the connections and connection pieces
respectively are made of parts produced separately in the injection
molding process whose edges are butt joined in a fluid-tight manner
by suitable welded or adhesive joints to the edges of the housing
which open out bell-shaped.
As is clear from FIG. 8, the blood chamber and the dialysate
chamber surrounding hollow fibers 55 are separated by a molding
compound 50. At its upper edge area, the molding compound has a
circumferential groove into which an O-ring 51 is inserted to seal
off the blood chamber from the dialysate chamber. As FIG. 8 clearly
shows, opening 53 leading into connection piece 52 is joined
directly to the lower side of O-ring 51, the annular space 54 used
for the supply and removal of the dialysate extending to the
O-seal, so that there is no dead space in which air bubbles could
collect.
The function of the invention will be described using blood as an
example of a fluid that requires the removal of impurities.
According to the present invention, blood enters the first fluid
flow space through a fluid port formed by connection piece 12. The
blood then travels through the first fluid path, which extends
through the molding compounds 7, 50, and exits through a second
fluid port. During the course of traveling through the first fluid
flow space the blood is cleaned of impurities, said impurities
diffusing into and being carried away by the dialysate in the
second fluid flow space.
Clean dialysate fluid is introduced into the second fluid flow
space through an extension 16 of the second cap 14 or through fluid
port 52. The dialysate spreads out in annular space 21, 54 and
flows through notches 5 into the portion of the second flow path
surrounding the first fluid flow path. Alternatively, the blood may
flow through bore holes 41 into annular space 37 and then through
second bore holes 39 into the portion of the second flow space
surrounding the first flow space. The dialysate and the blood may
flow in opposite directions (counter-current flow), or they may
flow in the same direction. As the dialysate moves through the
portion of the second flow space surrounding the first flow space,
impurities diffuse from the blood into the dialysate and the
impurity-laden dialysate exits the device through a second fluid
port.
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